1. Field of the Invention
The present invention relates to an air cleaner element capable of adsorbing fuel vapor generated in a carburetor and an intake manifold of an internal combustion engine, thereby preventing the emission of hydrocarbons into the surrounding atmosphere.
2. Brief Description of the Prior Art
So far there have been invented and demonstrated various types of air cleaners. In an air cleaner (1), a layer of activated carbon particles is securely attached to the interior surface of an air cleaner element comprising an air cleaning filter medium. In an air cleaner (2), a carbon element which contains activated carbon particles is located inside an air cleaning filter medium and spaced apart therefrom by a suitable distance. In an air cleaner (3), activated carbon particles are filled in an air intake pipe to the air cleaner.
When the activated carbon particles are incorporated into the air cleaners of the types (1), (2) and (3) and when the air cleaner is mounted on the carburetor, vibrations cause the wear and abrasion of the activated carbon particles so that finely divided activated carbon particles adhere to the carburetor, thereby adversely affecting the function thereof.
In the case of the air cleaners (1) and (2) wherein the layer of activated carbon particles is disposed within the air cleaner, it is required to provide a space sufficient to contain a volume of activated carbon particles required for adsorbing the fuel vapor. As a result, an air cleaner case must be increased in size. In the case of the air cleaner (2), the air cleaning filter medium must be reduced in size. It is difficult to increase the air cleaner case in size because of the space available in an engine room where other components also must be mounted. The reduction in size of the air cleaning filter medium cannot be allowed because of the resulting decrease in air cleaning capability. In order to effect the complete adsorption and desorption of the fuel vapor, the layer of activated carbon particles must be arranged in such a way that it may interfer with the flow of air. As described above, a sufficient surface area of the activated carbon particle layer cannot be obtained so that the velocity of air passing through the activated carbon particle layer increases when the engine is operating, thus resulting in the increase in resistance to the air flow and consequently the drop in the engine output.
Furthermore, the air cleaners (1), (2) and (3) are all complicated in construction and present the cost problem.